• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.4
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• pp.11-11
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• 2001

기존의 웨이브릿 기반 프랙탈 압축 방법은 전 영역에 대하여 최적의 정의역을 탐색하므로, 부호화 과정에서 많은 탐색시간이 소요되는 단점이 있다. 그래서 본 논문에서는 웨이브릿 변환영역에서 SAS(Self Affine System) 기법과 다중 스케일 인자를 이용한 웨이브릿 변환 기반 프랙탈 영상 압축 방법을 제안한다. 웨이브릿 기반 영역에서 정의역과 치역을 구성하고, 각각의 치역 블럭에 대해 모든 정의역 블럭을 탐색하는 것이 아니라, 정의역 탐색과정이 필요 없는 SAS 기법을 도입하여 공간적으로 같은 위치에 있는 상위 레벨 블록을 정의역으로 선택한다 그래서 부호화 과정에서 곱셈 계산량을 감소시켜 고속 부호화를 가능하게 한다. 그리고 SAS 기법의 단점인 화질이 떨어지는 단점을 개선하기 위해, 각 레벨별로 서로 다른 스케일 인자를 사 용하여 화질을 개선한다. 그 결과 화질에는 영향을 미치지 않고 부호화 시간과 압축률이 개선되고, 점진적 전송이 가능한 알고리듬을 제안한다.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.70-73
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• 1996

Many researchers had considered biological systems as linear systems. In many cases of biological systems, the phenomena that show the regular and periodic dynamics are considered the normal state. However, some clinical experiments reported, in some cases, the periodic signals represented the abnormal state. We assume that signals from human body system are generated from deterministic, intrinsic mechanisms and can be represented a simple equation that show nonlinear dynamics dependent on control parameters. The objective of our study is to model a nonlinear dynamics correctly from the nonlinear time series using the genetic programming method; to find a simple equation of nonlinear dynamics using collected time series and its nonlinear characteristics. We applied genetic programming to model RR interval of ECG that shows chaotic phenomena. We used 4 statistic measures and 2 fractal measures to estimate fitness of each chromosome, and could obtain good solutions of which chaotic features are similar.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.277-280
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• 2000

기존의 웨이브릿 기반 프랙탈 압축 방법은 전 영역에 대하여 최적의 정의역을 탐색하므로, 부호화 과정에서 많은 탐색시간이 소요되는 단점이 있다. 그래서 본 논문에서는 웨이브릿 변환영 역에서 SAS(Self Affine System) 기법을 이용한 웨이브릿 변환 기반 프랙탈 영상 압축 방법을 제안한다. 웨이브릿 변환영역에서 정의역과 치역을 구성하고, 각각의 정의역과 치역에 대해 모든 블록을 탐색하는 것이 아니라, 각 대역별로 공간적으로 같은 위치에 있는 블록을 정의역으로 선택한다. 이와 같이 웨이브릿 변환 영역에서 정의역 탐색과정이 필요 없는 SAS 프랙탈 영상 압축방법을 도입하여 부호화 과정에서 곱셈 계산량을 감소시켜 고속 부호화를 가능하게 하였고, 복호화 과정에서 각 레벨별로 서로 다른 스케일을 사용하여 화질을 개선하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.171-171
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• 2017

강우의 시간분포는 다양한 시간규모에 걸쳐 프랙털 또는 멀티프랙털 특성을 가지고 있음이 알려졌다. 기존의 연구는 주로 시간단위 이상의 프랙털 특성에 관한 것이었다. 실제로 극한 홍수를 가져오는 집중호우는 짧은 시간 규모에서 발생함에도, 이것에 대해서는 관측 자료가 제한되어 극소수의 실험적 연구만 가능했다. 본 연구에서는 기상청에서 제공한 고해상도(1분 단위) ASOS(Automated Synoptic Observation System) 자료를 이용하여, 강우 사상 안에서의 프랙털 특성을 분석해보았다. 대부분의 사상에서 단일 멱함수보다는 2개의 멱함수로 나누어지는 것이 밝혀졌으며, 나뉘는 시간 규모(T*)는 $3{\times}10$ 분으로 파악되었다. 이 시간 규모는 한 단위의 집중호우를 가져올 수 있는 구름크기의 물리적 상한과 관련이 있는 것으로 보인다. T*보다 작은 시간 규모에서의 멱함수 지수는 그 이후의 값보다 대체로 작은 것으로 나타났다. 이는 호우가 집중되는 기간의 변동성이, 강수가 물리적 한계에 도달한 이후보다 훨씬 작기 때문으로 보인다. 구체적인 멱함수의 지수는 강수의 발생과정과도 관련이 있을 것으로 추정된다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.10a
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• pp.365-373
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• 1999

Recently, numerous studies have demonstrated that artificial intelligence such as neural networks can be an alternative methodology for classification problems to which traditional statistical methods have long been applied. In building neural network model, the selection of independent and dependent variables should be approached with great care and should be treated as a model construction process. Irrespective of the efficiency of a learning procedure in terms of convergence, generalization and stability, the ultimate performance of the estimator will depend on the relevance of the selected input variables and the quality of the data used. Approaches developed in statistical methods such as correlation analysis and stepwise selection method are often very useful. These methods, however, may not be the optimal ones for the development of neural network models. In this paper, we propose a genetic algorithms approach to find an optimal or near optimal input variables for neural network modeling. The proposed approach is demonstrated by applications to bankruptcy prediction modeling. Our experimental results show that this approach increases overall classification accuracy rate significantly.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.82-95
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• 1998

In this paper, we propose a text-independent speaker identification system which has a classifier composed of two parts; to calculate the degree of likeness of each speech frame and to select the most probable speaker from the entire speech duration. The first part is realized using RBFN which is selforganized through learning and in the second part the speaker is determined using a con-tbination of MAXNET and delayed summings. And we use features from linear speech production model and features from fractal geometry. Closed-set speaker identification experiments on 13 male homogeneous speakers show that the proposed techniques can achieve the identification ratio of 100% as the number of delays increases.

• Journal of the Korean Mathematical Society
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• v.41 no.6
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• pp.945-955
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• 2004

In this paper, we establish a number system in $R^n$ which arises from a Haar wavelet basis in connection with decompositions of certain Cuntz algebra representations on $L^2$( $R^n$). Number systems in $R^n$ are also of independent interest [9]. We study radix-representations of $\chi$ $\in$ $R^n$: $\chi$:$\alpha$$_{ι}$ $\alpha$$_{ι-1}$…$\alpha$$_1$$\alpha$$_{0}$ ㆍ$\alpha$$_{-1}$ $\alpha$$_{-2}$ … as $\chi$= $M^{ι}$$\alpha$$_{ι}$ $\alpha$＋…M$\alpha$$_1$＋$\alpha$$_{0}$ ＋ $M^{-1}$ $\alpha$$_{-1}$ ＋ $M^{-2}$ $\alpha$$_{-2}$ ＋… where each $\alpha$$_{k}$ $\in$ D, and D is some specified digit set. Our analysis uses iteration techniques of a number-theoretic flavor. The view-point is a dual one which we term fractals in the large vs. fractals in the small,illustrating the number theory of integral lattice points vs. fractions.s vs. fractions.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.20-26
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• 2009

디젤기관에서 배출되는 유해배출성분인 NOx(Nitrogen oxides)와 PM(Particulate matter)은 기관 실린더내의 혼합기 분포에 의해 그 생성이 지배된다. 이 때문에 그 유해배출물들을 저감하기 위해서는 연소의 전단계인 혼합기 분포 및 그 생성과정의 해석은 매우 중요하다. 디젤기관에서 노즐로부터 분사된 연료는 주위기체와 혼합기를 형성하는 과정에서 액체에서 기체로 상변화를 동반한다. 따라서 분무의 혼합기형성과정을 해석하기 위해서는 액상과 기상을 동시에 분리하여 계측하는 것이 필요하다. 그러므로 본 연구에서는 디젤분무를 대상으로 Melton 등이 제안한 엑시플렉스(Exciplex) 형광법을 이용하여, 분무의 액상과 기상을 동시에 2차원분리해서 가시화촬영을 행하였다. 그 엑시플렉스 형광법을 이용하여 획득한 이미지에 화상 응용해석을 실시하여 비정상증발디젤분무의 혼합기형성과정에 대한 정보를 얻고자 하였다. 엑시플렉스 형광법을 이용해서 증발분무의 거동측성을 해석한 결과 프랙틸해석을 이용한 분무 흐트러짐(Disturbance)의 평가에서 플랙틸차원은 분사압력의 변화에 관계없이 하나의 값, 약 1.1로 정리 할 수 있고, 그 결과 각 분사압력에 대한 분무 기상외곽곡선(외주)은 거의 동일한 정도의 요철형상을 갖는다.

• Journal of Science and Technology Studies
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• v.3 no.2 s.6
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• pp.1-27
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• 2003

Complexity paradigm is a scientific amalgam that aims to unite a range of theoretical perspectives and research agendas across natural and social sciences. Proponents of complexity paradigm lay claims to an increasing number of areas of study, including artificial life, interpersonal networks, internal/international patterning of organizations, mapping of cyberspace, etc. All of those can be subsumed under the title, 'complexity turn.' Owing to the idea of open system, complexity paradigm has developed a number of new concepts/themes/perspectives that help to account for the complex mechanism of living and non-living creatures. A complex system comprises a number of properties such as disequilibrium, nonlinearity, dissipative structure, self-organization fractal geometry, autopoiesis, coevolution. Following a brief introduction to theoretical development, those properties are succinctly discussed. The complexity turn has provided a wealth of insights that enable to analyze system operations of any kind. It contributes a lot to illuminating the working of social system as well. The most remarkable attempt may be Niklas Luhmann's 'neofunctional system theory.' Merits and shortcomings of complexity paradigm were examined and its future prospect were assessed with the conclusion that complexity paradigm would continue to be useful both as effective transdisciplinary framework and powerful analytical tool.

• Journal of Oriental Neuropsychiatry
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• v.21 no.4
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• pp.21-39
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• 2010

Objectives : This study was to investigate the characteristics of the heart rate variability(HRV), types of insomnia and accompanying symptoms of 175 insomnia patients. Methods : For this study we carried out HRV, Inbody of 175 patients with insomnia who have come to Dongeui oriental hospital of Dongeui university from the period of Janaury 2008 to September 2010. We studied the association of the insomnia patients' age and gender with HRV, accompanying symptoms and the types of insomnia. The information of the accompanying symptoms and types of insomnia was based on each patients' progress note. Results : l. There was no significant differences in the characteristics of HRV between male and female. 2. The most frequent symptom shown among the insmonia patents' was headache(41.14%). 3. Comparing the symptoms between the gender, female patients had more dry mouth, alternative periodic chill and fever, and hot flush symptoms than the male patients. 4. Comparing the symptoms between the age groups(divided in two), the lower age group (20~59) had more dizziness and constipation symptoms than the higher age group (over 60). 5. Comparing the types of insomma between the age group, the higher age group (over 60) had more termination insomnia. 6. The types of insomnia of the entire insomnia patients were onset insomnia (73.1%), maintenance insomnia(20.6%), termination insomma(l7.1 %), shallow sleep (52.6%), listed by order of frequency. 7. The patients who takes hypnotics had more anorexia symptoms than the patients who doesn't take hypnotics. 8. There was no visible differences of the average fractal portrait between male and female. The age group of 20~30yrs. had the highest average fractal portrait, and the age group of 30~59yrs. the second highest, and the age group over 60yrs. the lowest. 9. The average of the regulation reserves of the autonomic nervous system(B2) - was lower than the regulation level of the ANS at the present (Bl). 10. When compared the priority of the function of the ANS, it showed that the proportion of HF($38.61{\pm}29.19%$)was the most, and than VLF($30.65{\pm}23.36%$), LF($20.04{\pm}19.13%$) the least. 11. The average of the compensation level of the central nervous system at present(Cl) - was lower than the compensation reserves of the CNS(C2). 12. The average of the control reserves of the cerebrum(D2) - was lower than the control level of the cerebrum at the present (Dl). 13. There was no visible differences between different sexes and ages in pulse rate. 14. The abdomen fat ratio above the line of the insomnia patients was 77.97% in male and 93.1% in female. Both sexes showed that insomnia patients had more abdomen fat that the standard, and female patients had more abd. fat than male patients. Conclusions : This study shows that the HRV of insomnia patients had no significant differences between gender. Fractal portrait, HF, LF and VLF of the insomnia patients are in inverse proportion to the age. The study of the Body Component Analysis showed that female had more abdomen fat than male, and both gender showed more abdomen fat than the standard. When looked into the accompanying symptoms of the insomnia patients, the symptoms show differences according to gender, age and hypnotics taking, as shown as below. In the entire patients, Headache was the most accompanying symptom. Female had more dry mouth, alternative periodic chill and fever, and hot flush symptoms than male. Higher age groups had more dizziness and constipation as accompanying symptoms than lower age groups. Patients who takes hypnotics had more anorexia than those who dont.